Chain approximation for the electronic density of states of amorphous and trigonal Se

Abstract

The electronic properties of spiral chains of Se atoms, in which the bond length, bond angle, and dihedral angle are the same for every atom, are investigated in the nearest-neighbour interaction approximation and are equivalent to those of a linear chain containing one atom per unit cell. The basis set used consists of one s and three p orbitals per atom. This model gives a good description of the overall features of the densities of valence states of the amorphous and crystalline forms because of their one-dimensional nature. The differences between the densities of valence states of the amorphous and crystalline forms can be explained by a change in the sign of the (pp pi ) interaction between the bonding p orbitals on adjacent sites. Although the s-p hydridization of each p band is estimated to be only 5%, the s bands strongly influence their shape.